In this Monday, Aug. 4, 2014, file photo, Nigerian health officials wait to screen passengers at the arrival hall of Murtala Muhammed International Airport in Lagos, Nigeria. A Nigerian nurse who treated a man with Ebola is now dead and five others are sick with one of the world's most virulent diseases, authorities said Wednesday.

ABUJA, Nigeria — A Nigerian nurse who treated a man with Ebola is now dead and five others are now sick with one of the world's most virulent diseases after coming into contact with him, the country's health minister said Wednesday.

The growing number of cases in Lagos, a megacity of some 21 million people, comes as authorities acknowledge they did not treat Patrick Sawyer as an Ebola patient and isolate him for the first 24 hours after his arrival in Nigeria last month. Sawyer, a 40-year-old American of Liberian descent with a wife and three young daughters in Minnesota, was traveling on a business flight to Nigeria when he fell ill.

The death of the unidentified nurse marks the second Ebola death in Nigeria, and is a very worrisome development since it is the Africa's most populous country and Lagos, where the deaths occurred, one of its biggest cities.

Meanwhile, Saudi Arabia's Health Ministry said a man who was being tested for the Ebola virus and has died. The 40-year-old returned Sunday from Sierra Leone, where there has been an Ebola outbreak, and was then hospitalized in Jiddah after showing symptoms of the viral hemorrhagic fever.

Spain's Defense Ministry said a medically-equipped Airbus 310 is ready to fly to Liberia to repatriate a Spanish missionary priest who has Ebola.

Ebola, which has no proven vaccine or treatment, has killed nearly 900 people this year in Sierra Leone, Guinea, Liberia and Nigeria and health officials in many countries are struggling to halt its spread.